• high-handed

• hide one's light under a bushel

• behind the times

• a latchkey child

• for himself and devil take the hindmost

• the power behind the throne

• a Jekyll and Hyde

• hunt high and low

• neither hide nor hair or it

• a highbrow

• behind your back

• behind the lines

• not for all the tea in China

• high and mighty

• devil take the hindmost

• behind closed doors

• put it behind you

• riding high

• on one's high horse

• behind the scenes

• for the high jump

• from the year dot

• a high flier

• talk the hind leg off a donkey

• fall behind

• high as a kite

• fight shy of

• spare the rod and spoil the child

• it is high time

• come hell or high water

• sky-high